Based upon careful study of the dynamics of heroin spread and maintenance in Chicago neighborhoods, we have developed a field research and intervention methodology for the detection, monitoring, and control of localized heroin epidemics. To date similar work has yet to be conducted in the area of polydrug abuse. In the present research we propose to develop an integrated program to explore systematically various facets of polydrug abuse and to monitor incidence and prevalence trends within target populations. Central to the proposal is a research-intervention model aimed at the eventual control of damaging patterns of illicit drug use in youthful populations. The first aim of the project will be to develop a functional and effective field team to gain access to polydrug using groups. We next propose to develop a set of operational field concepts appropriate to the populations under study. In this phase we will attempt to define the demographic, social, and psychological factors influencing incidence, prevalence, and spread of polydrug use. Thirdly, we propose to test a variety of outreach, intervention, and treatment referral strategies based upon our experience in the previous phases of the research. Finally, we will develop a framework for evaluation of treatment and outreach efforts which will be carried out at several levels. It will assess the effects of outreach and treatment on individual drug users, evaluate the success of the various modalities of treatment and referral utilized, and evaluate the impact of all these efforts on the incidence and prevalence of drug use in the communities under study. Testing devices, which we plan to group into a psychological testing battery, will describe the users that we contact on several dimensions: psychopathology, depression and self esteem, delinquency, IQ, and possibly organic brain impairment.